Continuous zinc-smelter.



W. McA. JOHNSON.

CONTINUOUS ZlNC SMELTER.

APPLICATION FILED FEB. 4, 19m.

Patented Oct. 30, 1917.

WITNESSES.

w 2 h Agg/vroz? f ATTORNEYS WOOLSEY MGA. JQHNSQN, 0E HARTFORD,CONNECTICUT.

CQNTIIIUQUS ZINC SMELTER.

Specification of Letters Patent.

Patented Oct. 30, 1%1'3'.

Application filed February 4, 1915. Serial 1i 0. 6,053.

To all whom it may concern Be it known that I, WOOLSEY Moll. donnsou, acitizen of the United States, and residing at Hartford, in the county ofHartford and State of Connecticut, have invented a new and ImprovedContinuous Zinc-Smelter, of which the following specification is a fulldisclosure.

. This invention deals with an apparatus for economically derivingvolatile metals, such as zinc, from ore or other material containingthat metal, and for doing so by a continuous smelting operation and insuch a manner that the metal will be rendered directly available in acommercially desirable state.

Zinkiferous ores have heretofore been smelted, by successive and quitedistinct operations, in such a way as to necessitate frequent handlingor manipulation of the material in subjecting it to the successivesteps, and the instrumentalities aiding in the general smelting schemehave heretofore been more or less segregated. All this has contributedto the high cost of the ultimately obtained metal.

Now, this invention seeks to render available a unitary orself-contained smelting plant or structure so designed that properlyconditioned ore may be continuously delivered into the receiving end ofthe struc ture, and be continuously treated therein to the end that zincwill be continually evolved and condensed directly into commerciallyavailable spelter at the delivery portion of the apparatus.

Another object is to formulate a system that will enable zinkiferousores, containing large amounts of iron and sulfur, together with smallamounts of copper and other valuable metals, to be smelted continuouslyand economically.

- This invention may be analyzed as com prising a continuous containerin the nature of a more or less complex and extensive retortsimultaneously subjected at its remote ends to widely differenttemperature conditions, 2'. e., by being externally but moderatelyheated by ordinary fuel near its charge-receiving end or non-fusing zoneand by being internally but intensely heated by electricity near itsmetal-yielding end or in its charge-fusing zone; said retort beingorganized to provide for a steady progression of a fusible chargetherethrough, whereby it may be successively subjected to widelydifi'erent temperature conditions; first, to efi'ectuate certainpreparatory endothermic reactions and, second, to bring the chargeultimately to a state of fusion to carry out the ultimate smeltingreactions. One of the dominant structural characteristics of thisinvention is that the container near its charge-receiving end is formedof zone is, on the other hand, confined by rel-' atively thickheat-insulating walls.

Continuing now by way of a more detailed description of one of thevarious possible embodiments of this invention, 1 indicates a preheatingapparatus which preferably occupies an elevated position, whichconveniently may be located immediately above the smelting furnaceproper 2. This relation may best be realized by providing a floor orelevated platform 3 which is held up by means of the pillars 4,constructed of channel iron or otherwise. The preheating dome 1 will beconstructed of fire-brick, or other suitable heat-resisting material,and internally it will contain or be constructed to provide a series ofpreheating floors 5, 6, 7 and 8. These floors are intended to receive alayer of the suitably prepared charge and they are so arranged that thecharge can be raked or rabbled or otherwise continuously fed from theuppermost to the lowermost levels in succession to expose fresh por=tions of the charge to the preheating con ditions. Conveniently, thismay be accom plished by providing each floor with a discharge port asindicated by 9, 10, 11 and 12 arranged in ofiset relation so that whenthe charge is rabbled oii of the floor 5 into the opening 9 it will fallonto the floor 6, and so on in succession from one to the other. Toprevent furnace gases and air from oxidizing the charge while it is beinheated a series of roofs 13, 14, 15 and 16, c osed off by side walls 17,18, 19, 20 and 21, may be provided, thereby forming a closed continuousconduit for the charge. The charge is suitably caused to progress, asbefore stated, and to enable this to be done a series of rabble doors22,23, 24' and 25 open through the external walls of the preheating domeand by means of suitable passageways permit access to the various floorsto enable the rabbling to take place.

The above structure is intended to be used as a means instrumental incarrying out an important metallurgical change in the zinkiferousmaterial. That is to say, I intend, as a preliminary to the actualsmelting operation to efiect a metallurgical change in the condition ofthe ore, rendering it more suitable for economic smelting. Thezincbearing charge, for example, after having its sulfur content reducedto a point materially less than will ordinarily exist in the native ore,and materially greater than is customary after the roasting operation ofretort smelting, is mixed with a suitable amount of carbon, preferablycapable of evolving enough gas to cause a draft in the preheating, andis then caused to pass through the preheating dome 1 by being admittedthrough the port 26, whereby it will be exposed to a temperature ofabout 1050 degrees. This temperature will suffice, during the timeinterval consumed by the passage of the ore, to reduce certain productsin the charge and materially change its metallurgical condition as byforming a highly reactive sponge iron and yet without evolvingsubstantial quantities of zinc vapors. During this passage,substantially all of the cadmium will be reduced and evolved as a vaporand carried to the point of collection by the hydro-carbon gases givenoff by the charge.

The composition of the charge and the metallurgical steps and reactionsinvolved are fully disclosed in my copending application, Serial No.854,169, filed July th,

1914, and reference thereto is herein made as a part of this applicationand to avoid the necessity of repetition.

It is noteworthy that the heat utilized for the foregoing step isderived directly from the combustion of fuel, as distinguished from thetransformation of electricity, and this has many advantages. To thatend, a combustion chamber A is formed by the walls D of suitableheat-insulating material and through a suitable door C the fuel is fedonto the grate B. The products of combustion pass up a chimney formed ofthe heat-insulating walls F and preferably through a suitablechecker-work E which acts as a thermal balancewheel and maintains aneven temperature, even though the firing on the grate B should beirregular.

These products of combustion are in a very highly heated condition,though not sufficiently so as to cause the ore mixture in the preheatertobe completely smelted, although such mixture may be partially smeltedso as to practically eliminate certain valuable elements before themixture reaches the secondary or more int nsive smelting operation,which, in this embodiment, is carried out in an electric furnace whereinzinc is smelted. The flame and waste gases now follow the courseindicated by the arrows a.bcdefgh and 2' and thus pass from the flue Gto the chimney H so as to circulate around the retorts and transmit theheat through the thin heat-conducting walls thereof and thereby preheatthe charge in said retorts. It is noteworthy that the current of wasteheatyielding gases travels conversely to the current of heat-absorbingmixture, thereby making for efliciency.

The preheated mixture now passes to the intensive smelting zone in whichare recovered certain more refractory elements, such as zinc, magnesium,iron, etc. An electric furnace is shown for carrying out this step. Animportant characteristic of this invention lies in the unitaryconstruction of the apparatus whereby the preheating and intensivesmelting zones are formed in one unitary structure. This makes for apractically continuous and uninterrupted treatment of the material to besmelted.

When the material reaches the last stages of the preheating operation,it enters the chute 30 which leads downwardly into the electric furnace31 formed of the bottom 32, the side walls 33 and the dome 34. One ormore doors or dampers 35 control the rate of passage into the intensivesmelting zone, wherein the material is reduced to yield a lowermost lathor layer of the heavier metals or products which may be periodicallytapped through the tap-hole 36. Less heavy reduction products, such ascopper or iron sulfids (so-called matte), will float upon the lowermostbath and may, in turn, be withdrawn through the tap-hole 37; and in likemanner the uppermost bath of slag will be tapped out through theslag-monkey 38. This bath of slag is maintained at the smeltingtemperature by means of an electric current conducted by the electrodes39 and 40 which are fed into the electric furnace as fast as needed bysuitable feeding means.

The zinc reduced by the solid carbon in the electric furnace isvolatilized and passes through the outlet vent 40 into the chamber 41 ofthe conduit 42 connecting the electric furnace with the chamber 43 ofthe condenser 44, wherein the zinc vapor is condensed and withdrawnthrough the part 45. Excess vapor-pressure is relieved by means of theprolong 46. The condenser is maintained at the proper temperature bymeans of hot gases generated in the combustion chamber 47 by fuelburning on the grate 48. These gases take the course indicated by 7c-Lmn/0-p'r-s and t and maintain the condensing chamber at the temperaturebest adapted to yield cohesive metal.

instance Having thus revealed this invention 1 claim as new and desireto secure the following combinations of steps and elements, orequivalents thereof, by Letters Patent of the United States l. A unitarysmelting apparatus combining an electric furnace having heat-insulatingWalls; a preheating retort having heatconducting thin Walls andconnected with said furnace whereby snieltable material may be preheatedin said retort and passed directly into said furnace Without beingexposed to air; and a fuel-burning furnace ar ranged to heat saidretort; and a condenser adapted to receive all the gaseous prcducts fromsaid furnace.

2 A unitary smelting apparatus comloining'an internally heated electricfurnace; a preheating retort adapted to retain a granulated smeltalolematerial; a fuel-burning furnace for externally firing said retort; adrop-chute hermetically connecting said re tort and electric furnace,whereby preheated material may gravitate through said chute into saidfurnace; and a condenser arranged to receive all gases from saidelectric furnace independently of said fuel-burning furnacea 3. Aunitary smelting apparatus cornhining an internally heated electricfurnace; a series of retort-sections arranged zig-zag and hermeticallyconnected with said electric furnace; and a fuel bug furnace forexternally firing said retort-sections.

4:. A combined electric and fuel smelting apparatus comprising anelectric furnace; a condenser connected therewith to receive all gasestherefrom; a preheating retcrt independent of said condenser adapted tode= liver preheated material into said furnace; and an independentfurnace for heating said preheater. 5, A smelting apparatus combining anelectric furnace; a preheater superimpose thereover; means for rablolingmaterial in said preheater; an independent furnace for heating saidpreheater; and a condenser for receiving all gases evolved in saidelectricfurnace In Witness whereof, I hereunto suhscrihe my name, asattested by the two subscribing Witnesses.

WQQLSEY McA. JQHNSUNQ Witnesses:

l/L Q11 Ccornn, Gconn,

All

